The 2-cyanoacrylate adhesive composition quickly establishes a strong bonding between various types of materials attributed to the unique anion polymerization characteristics exhibited by its principal component, 2-cyanoacrylic acid ester, which initiates polymerization under the presence of weak anion provided by slight moisture or the like attached to a surface of an adherend. Accordingly, it is used as the so-called instantaneous adhesive in a wide range of fields including industrial, medical, and household applications. However, because this adhesive composition is inferior in heat resistance and water resistance, there is a problem of lowering the adhesion strength when bonded articles are used under a severe environment.
To overcome these problems, modification methods have been proposed heretofore, which include adding various types of additives. For example, Patent Document 1 discloses an adhesive composition which comprises a 2-cyanoacrylic acid ester to which at least one compound selected from aromatic polycarboxylic acids and anhydrides thereof is added. Furthermore, Patent Document 2 discloses phthalic anhydride as a specific additive that improves adhesion durability under humid or high temperature environment. Further, Patent Document 3 discloses a cyanoacrylate adhesive composition which contains a 2-cyanoacrylic acid ester and a hydrogenated anhydride to improve heat resistance.